1. Field of the Invention
This invention pertains to a process for the production of a soldered joint between a carbon part or material and a silicon carbide part, particularly the soldering of flat parts that have their greatest thermal expansion in the flat plane in which the solder is also so arranged, for example, as in a sliding ring and a supporting ring in a dry gas seal.
2. Discussion of the Background of the Invention and Material Information
U.S. Pat. No. 5,092,612 to VICTOR describes, in detail, the function of a dry gas seal in which the sliding rings are comprised of silicon carbide, whose frontal face areas can have a protective seal or emergency contact layer of several .mu.m comprised of graphite or polytetrafluoroethylene. The layers are provided in case that the sliding surfaces touch each other in an emergency running situation.
Dry gas seals are dynamic seals in which a load carrying gas cushion is first built up between the running surfaces during the relative movement of the sliding surfaces. During start up and coast down of a shaft, equipped with dry gas seals, there is almost always a very short emergency running situation which leads to a mechanical contact followed by a shock-type of temperature increase of the sliding surfaces. A unitary carbon sliding ring or body, due to the good running/sliding properties of carbon would, in theory, be advantageous, but in actual operating conditions suffers from excessive deformation.
On the other hand, protective layers in the magnitude of several .mu.m have a very short life span since they may generally already be consumed during the run-in period of the sliding ring.